Significance of frequency in quantifying the deterioration in the properties of SBS modified binders and rutting performance. (30th November 2020)

• Record Type: Journal Article
• Authors: Singh, Sumit K.; Pandey, Akanksha; Sohel Islam, Sk.; Ransingchung R.N., G.D.; Ravindranath, Sham S.
• Is Part Of: Construction & building materials. Volume 262(2021)
• Publication Date: 2020-11-30
• Subjects: SBS, Styrene butadiene styrene -- PMB, Polymer Modified Binder -- FSM, Frequency Sweep Measurement -- TSM, Temperature Sweep Measurements -- PG, Performance Grading -- MSCR, Multi Stress Creep Recovery; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2020.120872
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: SBS molecules degrade in asphalt binders within 3–5 days of storage at 180 °C. Property erosion in SBS modified binders increases the rut depth in asphalt mixture. Degradation of SBS polymers is visible at test ω ≤ 0.1 rad/s and temperatures > 50 °C. At ω ≤ 0.1 rad/s, the rheological parameters correlate well with rut depth. For PMBs, it is important to have a rheological parameter at ω ≤ 0.1 rad/s. Abstract: The softening point and % elastic recovery of SBS modified binders (SBS-MB) decrease by up to 12 °C and 30%, respectively, within 7 days of storage at 180 °C due to the thermal degradation of the SBS molecules. The rut depth nearly doubles in asphalt mixes prepared using the SBS-MBs stored at 180 °C for 7 days. Contrary to the observed property deterioration, the rheological parameters measured at the frequency (ω) = 10 rad/s, exhibit only minor changes. Analysis through frequency sweep measurements (100–0.01 rad/s), reveal that the rheological properties essentially overlap at ω ≥ 1 rad/s, and the property erosion is mainly evident at ω ≤ 0.1 rad/s and test temperatures > 50 °C. The observed result implies that the binder molecules and the shorter segments of the SBS molecules dominate the rheological response at ω ≥ 1 rad/s due to which the rheological curves overlap. It is evident from the study that at upper service temperature, a rheological parameter measured at ω ≤ 0.1 rad/s is essential for good quality control, grading, and performance evaluation of polymer modified binders (PMBs). This study provides valuable insights that are beneficial for the pavement construction industry.